Lee Ermey doesn't need to win an Oscar to know that his portrayal of a brutal, sewer-mouthed drill instructor in Stanley Kubrick's Full Metal Jacket is searingly authentic. At the premiere party in Los Angeles, a woman who'd just seen the film approached Ermey's wife, Nila, her eyes brimming with sympathy. "Good grief, is he like that at home?" asked the woman. Laughs Ermey: "She figured I'm just a nasty, horrible son of a bitch."

Well, she was wrong. Ermey, 43, may be a leathery, Nam-wounded vet for whom the American flag always flies high, but there's a gentle, easygoing soul inside that ramrod-straight, rough-as-a-gator exterior. Of course it isn't difficult to see how the woman was misled. As Marine Gunnery Sgt. Hart-man, Ermey dominates Full Metal Jacket like a tank at a tea party, relentlessly taunting his Vietnam-era recruits to toughen them for their coming ordeal. "I just basically tore 'em a new asshole," says Ermey, whose character makes Hollywood's second-nastiest drill instructor, An Officer and a Gentleman's Lou Gossett Jr., seem like a battle-fatigued Mary Poppins.

According to the New York Times, Ermey is "a stunning surprise—so good that you might think he wrote his own lines." Good call. Much of the nonstop invective he spews onscreen is taken verbatim from his days as a D.I. In the mid-'60s, at the height of the Vietnam buildup, Ermey spent 30 months at San Diego's Marine Corps Recruit Depot, force-feeding spit shines and double-times through the medium of his twangy, hardass patter. "Mothers of America," Ermey says in mock apology for his excesses, "I'm terribly damn sorry. But either we could undertrain your young son and send him to Vietnam, where he'd be sure to get killed in three days, or we could be a little tougher on him, and maybe he'd survive and come home."

Ironically Kubrick, who had hired Ermey only as technical adviser, didn't think he was mean enough for the part. But Ermey, who'd existed on the fringes of the movie business for a decade, was ready for a shot. "I put the Smokey Bear hat on, got nose-to-nose with the recruits and went into an accelerated mode of harassment."

He got the part—then almost lost it. During a February 1986 late-night pizza run near London, where the film was being shot, Ermey's car hit an ice patch and traveled 100 feet across a sleet-slick golf course before smashing head-on into a tree. Ermey was trapped inside for two hours before being rescued. His collarbone and six of his ribs were broken; his left lung had collapsed and he was bleeding internally. He says he was sure Kubrick would find another actor to play Hart-man. Instead, with the film half shot, the director shut down production and for three months helped Ermey recover, even sending him to a $700-a-night health farm.

On his first day back on the set, Ermey whacked his chest on an obstacle-course crossbar, then felt a snap and a sharp pain. One of the ribs had re-cracked. Ermey sucked it up and didn't say a word until the rib healed three weeks later. The Protestant work ethic, leatherneck style.

Born in Emporia, Kans., the second of J.E. and Betty Ermey's six sons, Lee grew up on his parents' farm and began driving a tractor at age 7. When he was 11, his father sold the farm and took a construction job in Zillah, Wash., where Lee became the family's rowdy black sheep. By his 17th birthday he'd been hauled into court three times for joyriding, fighting and underage drinking. "Join the military," said the judge, "or I'm going to have to do something to you."

The Marine Corps not only "put a screeching halt on my unconventional manner," as Ermey dryly notes, it provided what he thought was going to be a career. Made a staff sergeant at age 24, he followed his D.I. stint with a tour in Nam—a hitch that ended in 1969 when shrapnel tore up his right shoulder and back. Because of his wounds, Ermey was prematurely retired in 1971 after 10 years of service.

"I wasn't prepared to get out," says Ermey, who was then 27. "It's the most depressing thing in the world when you're a staff NCO, which is very prestigious, and the next day you find yourself busing tables." His other jobs included short-order cook in Yakima, TV commercial pitchman in Manila (where he met his future wife, Nila, in 1977), and nuclear plant quality-control engineer near Benton City, Wash. He added acting to his résumé in 1976, when Francis Coppola landed in the Philippines and hired him as an extra in Apocalypse Now. Always shuttling between jobs, Ermey served as technical adviser and small-role actor in The Boys in Company C(1978) and Purple Hearts(1984) before trying out for Full Metal Jacket.

He made enough money from the movie to buy his first house, a three-bedroom, brick-front ranch in Palm-dale, Calif., on the edge of the Mojave Desert, where he and Nila, 30, live with their kids, Betty, 8, Evonne, 6, and Clinton, 5.

How is Ermey reacting to his sudden prominence? "I think he's not sure how to handle certain aspects of it," says his friend, screenwriter Rick (Purple Hearts) Natkin. "He's apprehensive about being viewed as some sort of oddity. On the other hand he's anxious to let the publicity surrounding the movie work for him." It may do that. Each day's mail brings scripts to read, an estimable perk for a man whose movie career has been iffy at best. And in case none of the scripts works out, Ermey is writing a story about an ex-D.I. who can't adjust to civilian life. "There's damn sure a role in it for me," he grins. "If Sylvester Stallone can do it, I can."